Closing mechanism for an electric circuit breaker



Aug. 5, 1958 T. R. COGGESHALL ETAL 2,846,621

CLOSING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Filed Sept. 19, 1956 3Sheets-Sheet l Inventors: Th el 1 we I I P. Co ggesh al I,

Ugo R. T021": e l I a by W Th ei rthorn e9.

Aug. 5, 1958 T. R. COGGESHALL ET AL 2 CLOSING MECHANISM FOR AN ELECTRICCIRCUIT BREAKER Filed Sept. 19, 1956 3 Sheets-Sheet 2 Inventors:

Thelivvell F2. Goggeshall,

Ugo -R'l o gfiella,

Attorney.

1958 T. R. COGGESHALL ETAL 2,846,621

CLOSING MECHANISM FOR AN ELECTRIC CIRCUIT BREAKER Filed Sept. 19, 1956 3Sheets-Sheet 3 Inventors: TheHweH R.Coggeshall Ugo FlTognHa,

The I -rttoP'r-v e H United States Patent CLOSING MECHANISM FOR ANELECTRIC CIRCUIT BREAKER Thellwell R. Coggeshall, Cynwyd, and Ugo R.Tognella,

Philadelphia, Pa., assignors to General Electric Company,.a corporationof New York Application September 19, 1956, No. 610,736 7 Claims. (Cl.317-54) This invention relates to a closing mechanism for an electriccircuit breaker and, more particularly, to a control arrangement forcontrolling the operation of such a mechanism.

As a general rule, if a circuit breaker is closed on a fault andautomatically trips open in response to the presence of the fault, it ismost important that it remain open and not repeatedly attempt to close.As is well known. such repeated reclosing operations, commonly termedpumping, can lead to serious damage both to the breaker and the system,especially if allowed to continue.

Numerous control schemes heretofore have been devised "for preventingsuch pumping action, but, most frequently, they have been complicatedand expensive and have involved the use of a number of costlymultiplecontact relays.

Accordingly, an object of our invention is to provide for a circuitbreaker a simple and inexpensive control scheme which operates toprevent circuit breaker pumping.

Another object is to provide an anti-pump control scheme which does notrequire the use of expensive relays.

Another object is to construct the control scheme in such a manner thatit can utilize a small, inexpensive and non-continuously-ratedelectromagnetic device for initiating circuit breaker operation.

In carrying out our invention in one form, we provide an electriccircuit breaker which has motive means operable to produce closing ofthe breaker. This motive means is controlled by the action of anelectromagnetic device having a driving part operable from a neutral toan operated position- This movement of the driving part is transmittedto a control linkage which responds thereto by causing the motive meansto operate to produce cir' cut breaker closing. The control linkage isso constructed that it is inelfective to again cause a breaker closingoperation so long as said driving part is held in its operated position.The driving part is moved into its operated position by closing aselectively-operable switch in an ene'rgizingcircuit for theelectromagnetic device. This also results in a seal-in circuit beingestablished for the electromagnetic device, and this seal-in circuitholds the driving part in its operated position. The seal-in circuit ismaintained so long as the selectively-operable switch is held closed,and, as a result, further closing operations of the circuit breaker areprecluded so long as the switch is held closed.

For a better understanding of our invention, reference may be had to theaccompanying drawings taken in connection with the followingspecification, wherein:

Fig. 1 is a perspective view illustrating one form of circuit-breakerclosing mechanism embodying our invention. The mechanism is shown in thebreaker-open position.

Fig. 2 is a wiring diagram schematically illustrating a control circuitfor the mechanism of Fig. 1. The various components of the controlcircuit are shown in the position which they would occupy when themechanism is in the position of Fig. 1.

Patented Aug. 5, 1958 "ice Fig. 3 is a cross-sectional view illustratingcertain details of the closing mechanism.

Fig. 4 is an exploded schematic view illustrating the mechanism and itscontrol circuit upon the completion of a closing operation.

Fig. 5 is a wiring diagram illustrating a modified form of ourinvention.

Fig. 6 schematically illustrates another modified form of our invention.

Referring now'to Fig. l, the circuit breaker shown therein comprises areciprocable contact-actuating rod, or switch member 8, which is biasedto the open-circuit position shown by means of a suitable opening spring9. For transmitting closing thrust to the actuating rod 8, there isprovided aconventional trip-free linkage L which comprises a pair oftoggle links 10 and 12 pivotally joined together at a knee 14. One ofthe toggle links 12 is pivotally connected at its opposite end to abell-crank 15, which, in turn, is pivotally connected to thereciprocable contact-actuating rod 8. The other toggle link 10 isconnected by a pivot pin 18-tothe upper end of a guide link 19'. Thisguide link 19 is pivotally supported at its lower end on a fixed fulcrum20. Thepivot pin 18 carries a latch roller 21 which cooperates with asuitable trip latch 22, which is arranged to be operated in response topredetermined circuit conditions by means of a suitable conventionaltripping solenoid 23. So long as the trip latch remains in the latchedposition shown in Fig. 1, the toggle 10, 12 is capable of transmittingthrust to the movable contact-actuating rod 8. Thus, when the knee 14 islifted from the position shown in Fig. 1, the toggle 10, 12 is extendedand drives the contact-actuating rod 8 to the left toward closedposition against the bias of opening spring 9.

This lifting of the knee 14 is accomplished by the action of a rotatablecam 24 cooperating with the usual roller 25 which is mounted at the knee14. When the cam 24 is rotated clockwise through a complete revolutionby means soon to be described, it moves from the position of Fig. l tothe position of Fig. 4 and lifts the knee 14,

. thereby extending the toggle 10, 12 and closing the breaker. Fig. 4shows this toggle portion of the breaker mechanism in closed position,where it is held by the force of the cam acting through the knee 14 tomaintain the toggle 10, 12 extended.

Should the trip latch 22 (Fig. 1) be tripped when the breaker is closed,or even during the closing stroke, the toggle 10, 12 will be renderedinoperative to transmit closing thrust to the contact-actuating rod 8.As a result, the opening spring 9 will be free to drive thecontactactuating rod 8 to its open-circuit position. A suitableresetting spring 27 cooperates with the guide link 19 to reset themechanism L to the latched position (shown in Fig. 1) after it has beentripped.

For rotating the cam 24 to drive the circuit breaker closed, there isprovided a stored-energy closing device which comprises a torsion spring30 suitably coupled at one end to the cam 24. As shown in Fig. 1, thiscoupling comprises a disc 31 attached to the cam shaft 32 and carrying apin 34 to which the forward end of the spring is suitably anchored. Therear end of the spring is anchored by a suitable pin 34a to a rotatablesprocket 35.

Charging of the spring 30 is accomplished by rotating the sprocket 35 ina clockwise direction by means of a suitable charging motor 36 coupledto the sprocket 35 by means of a conventional chain drive 37. The mannerin which this charging motor is controlled will appear more clearlyhereinafter. Unwinding of the spring 30 at its rear end by possibleback-tracking of the sprocket 35 is prevented by means of a suitableholding pawl 38.

For controlling the rotation of the cam 24, there is provided a latch orclosing release prop 40 which cooperates with an abutment such as theroller 41 suitably secured to the cam 24. This prop 40 is keyed to anactuating shaft 42 which is journaled within a U-shaped bracket 43. Theprop is biased into its holding position shown in Fig. 1 by means of aprop-resetting spring 44 surrounding the shaft 42. When the prop 40 isreleased, i. e., moved clockwise out of the path of the abutment 41, themain spring 30-is free to drive the cam 24 clockwise at high speed fromthe breaker-open position of Fig. l. The prop 40 is reset to its holdingposition immediately and in ample time to arrest the movement of the cam24 after it has rotated through a complete revolution to drive thebreaker into the closed position shown in Fig. 4.

For releasing the prop 40 to produce the above-described breakerclosingaction, a releasing device 50 is provided. This releasing device 50 isclaimed in application Serial No. 612,007, now Patent No. 2,820,119,Miller et al., filed September 25, 1956, and assigned to the assignee ofthe present invention, and reference may be had to that application fora complete description of its details and advantages.

The following brief description of the releasing device 50 is believedto be adequate to convey an understanding of the present invention.Referring to Fig. 1, the releasing device comprises a guide link 51mounted for pivotal movement about a fixed pivot 52 and carrying at itslower end a transversely-extending actuating pin 53. Pivotally mountedon this pin 53 is an actuating pawl 54, which has a transverselyprojecting portion 55 contacting the rear side of the guide link 51. Theprojecting portion 55 is releasably held in this position by a spring 57which allows the pawl to rotate counterclockwise about the pin 53 ofFig. 1 under certain conditions, which will soon be described. Theactuating pawl 54 cooperates with a pin 59 carried by a crank 60 securedto the prop actuating shaft 42. When the actuating pin 53 is moved in acounterclockwise direction about its pivot 52 from the position of Fig.l, the actuating pawl, with its lower surface 54a acting through thecrankpin 59, rotates the crank 60 in a clockwise direction and therebyreleases the prop 40. The lower surface 54a of the actuating pawl is soshaped that as soon as it effects this releasing action, it moves freeof the crankpin 59 and permits the crank 60 to be returned to itsoriginal position by means of the prop resetting spring 44. This, ofcourse, results in the prop being immediately reset in time to arrestthe movement of the main cam 24 after it had been spring driven througha complete revolution to effect breakerclosing. The parts of thereleasing device would occupy the position shown in Fig. 4 immediatelyafter the prop had been released and had reset.

This prop-releasing action ,of the pawl 54 is produced by means of aslidable, suitably-guided L-shaped operating rod 62 which is coupled tothe actuating pin 53 by means of a connecting link 63. This connectinglink 63 at one end is pivotally mounted on the actuating pin 53 and atits other end has a slot 64 which receives the outer leg of theoperating rod. A compression spring 65 acting through the operating rod62 maintains the parts of the releasing device in the normal or neutralposition of Fig. 1 against the opposing bias of a weaker tension spring66, which tends to move the actuating pin 53 counterclockwise about itspivot 52.

For actuating the operating rod 62, a solenoid 67 having its armature,or driving part, 67a secured to the outer end of the operating rod 62 isprovided. When this solenoid 67 is sufficiently energized, it acts, withthe aid of spring 66, to move the operating rod 62 through its normalstroke to the right from the neutral position of Fig. 1. This motion istransmitted through the connecting link 63 to move the actuating pin 53counterclockwise about its pivot 52. This drives the pawl surface 54ainto engagement with the crankpin 59 and produces the propreleasingaction described above. After release, the prop 40 immediately resets,as described above, and the parts of the releasing device 50 are then inthe position of Fig. 4. When the operating rod 62 is thereafterreleased, the releasing device 50 resets under the influence of itsspring 65, and the parts thereof are restored to their position ofFig. 1. During prop-releasing action, the pawl 54 acts against the pin59 in an essentially unyielding manner due to engagement between theprojection 55 and the guide link 51 as the actuating pin 53 movescounterclockwise. When the device is reset from Fig. 4, however, thepawl yields when it engages the crankpin 59, since the crankpin is thenon an opposite side of the pawl. This yielding action continues untilnear the end of the resetting stroke, at which time the pawl has beendragged clear of the crankpin 59 and is free to reset under a theinfluence of its own spring 57.

It should be apparent from Fig. 4 taken in connection with the abovedescription that the releasing device 50 is incapable of again releasingthe prop 40 so long as its driving part, the armature 67a, is held inthe position of Fig. 4 inasmuch as the crankpin 59 is then behind thepawl 54. To again release the prop 40, it is necessary to first resetthe releasing device 50 along with its driving part 67a at leastpartially to the position of Fig. l, as described in the precedingparagraph.

For controlling the charging motor 36 and for ensuring against operationof the releasing device 50 before the motor 36 has charged the spring 30to a safe energy level, a controlling arrangement 70 has been provided.This controlling arrangement is claimed in application S. N. 611,331,Miller et al., and its details form no part of the present invention. Itis "believed, however, that a brief description of its construction andoperation would facilitate an understanding of the present invention.Referring to Fig. 3, this controlling arrangement 70 comprises a nut ornut-like member 72, which preferably is formed as a tubular sleevehaving a screw 72:: projecting radially into its bore. As shown in Fig.3, the nut is coupled to the breaker-operating cam 24 by means of acalibrating rod 73, coaxial with the tubular cam shaft 32, and pinned at74 and 75 to the nut 72 and the cam shaft 32, respectively. Meshing withthe nut 72 is a threaded controlling rod 76 which is coupled to thespring-charging sprocket 35 for rotation therewith but is free to moveaxially with respect to the sprocket. The coupling between the sprocket35 and the threaded member 76 comprises a crank 77 shown welded to thethreaded member 76 and carrying at its outer end a crankpin 78 which isslidably received in a boss 79 carried by the sprocket.

Referring to Fig. 3, if the sprocket 35 together with the threadedcontrolling member 76 is rotated in a springcharging direction, then thenut 72 will act to shift the threaded controlling member axiallyoutward. Conversely, if the breaker operating-cam 24 is thereafterreleased, its rotation will cause nut 72 to return the controllingmember 76 axially inward to the position shown in Fig. 3. The manner inwhich this axial movement of the controlling member 76 is utilized willsoon appear more clearly.

As will "be apparent from Fig. 3, the threaded controlling member 76 hasa tubular outer end which is slidably supported on the inner end of thesprocket shaft 26. A push rod 85.is loosely mounted in the coaxial boresof the tubular shaft 25 and the tubular controlling member 76.Cooperating with the push rod and formingan additional part of thecontrolling arrangement 70 is a T-shaped switch-actuating lever 88. Asshown in Fig. 3, this actuating lever 88 is pivotally mounted on thestationary framework 27 by means of a pivot 89 and is biased in acounterclockwise direction by a torsion spring 90. For reasons whichwill soon appear, this lever 88 serves to actuate a pair of switches 92and 94 in response to appropriate'axial movement of the push rod 85.

As shown in Fig. 4, the switch 92 is a normally biasedv closed switchwhich is connected in series with the charging motor 36 across asuitable current source 95. The switch 94, on the other hand, is anormally biased-open switch which is connected across the current'sourcein series with the coil of solenoid 67 and with a manuallyoperableswitch 96. Because of their respective functions, the switch 92 ishereinafter termed the motor-controlling switch and the switch 94 istermed the releasing-device controlling switch.

As shown in Figs. 2 and 4, the releasing-device controlling switch 94 isshunted by means of an impedance in the form of a resistor 105. Thisresistor 105 is of such a size that when the control switch 94 is open,the resistor allows sufficient current to flow through the coil ofsolenoid 67 to maintain its armature 67a sealed-in should the armaturethen be in its operated position of Fig. 4. Thus, so long as an operatorholds the switch 96 closed, the releasing device 50 remains in theposition of Fig. 4 in spite of opening of the control switch 94 duringspring-discharge. As long as the releasing device 50 is held in thisposition of Fig. 4 and is not permitted to reset, it is incapable ofreinitiating another operation of the stored-energy device 30-35, aspreviously described.

The resistor 105 is also of such a size that, should the control switch94 be open, the resistor limits the current flowing through the coil ofsolenoid 67 to a value which is insufiicient to cause pick-up of thesolenoid armature, i. e., movement from its normal-deenergized positionof Fig. 1 to its operated position of Fig. 4. As a result, if thesolenoid armature 67a is in its normal deenergized position of Fig. 1and the control switch 94 is then in its open position, closing of theswitch 96 will be ineffective to produce solenoid operation.

Operation of the control arrangement 70 is as follows. Assume first thatthe main spring 30 has been discharged and the operating mechanism hasjust moved into the position of Figs. 3 and 4. The normally-closed motorswitch 92 would then be closed and the motor would be driving sprocket35 in such a direction that the threaded controlling member 76 would bemoving axially outwardly due to its meshing engagement with the nut 72.This axially-outward movement of the controlling member 76 istransmitted through the push rod 85 to the switch actuating lever 88 andacts to open the motor-controlling switch 92 when the spring has beencharged to a predetermined safe energy level. This motor cut-otfterminates the charging operation, except for a slight amount ofovertravel, after which the parts occupy the neutral position of Fig. 1.

As shown in Fig. 4, during the time that the main spring 30 was in theabove-described discharged condition, the releasing-device controlswitch 94 was open and, thus, the manually-operable switch 96 wasrendered inefiective to produce energization of the closing-release coil67. Accordingly, electric operation of the releasing device 50 wasprevented during this interval, and thus the danger of premature releaseof the main spring 30 was obviated. The releasing-device control switch94 is so adjusted that just prior to motor cut-off during aspringcharging operation, it is closed by the action of theswitch-actuating lever 88. As a result, when the parts have beenmotor-driven from position of Fig. 3 into the position of Fig. 1, asdescribed in the preceding paragraph, the releasing-device controlswitch 94 is closed and no longer acts to disable the manually-operableswitch 96. With the control switch 94 closed (assuming the switch 107also to be closed), the manually-operable switch 96 can be selectivelyoperated to again release the mainv spring 30 and close the breaker ifit is then open.

When the releasing device 50 is operated to permit the main spring 30 todischarge, the resultant rotation of the nut 72 quickly withdraws thecontrolling member 76 from its extended position of Fig. 1. This allowsthe torsion spring 90 to drive the control-switch actuating lever 88together withthe push rod 85 into the position 6 shown in Figs. 3 and 4.This closes the motor control switch 92 and thereby initiates aspring-charging operation of the typedescribed above.

In order to prevent attempted closure of a circuit breaker whenever itis already closed, it is customary to provide the breaker with a bswitch connected in series with the breakers closure-initiating device.Such switches are customarily actuated by the circuit breakers operatingmechanism and are open when the breaker is closed and closed when thebreaker is open. We have shown such a b switch in Figs. 1, 2 and 4 at107. As can be seen in Figs. 2 and 4, this b switch 107 is connected inseries with both the manually-operable switch 96 and the coil of theclosing-release solenoid 67 and in parallel with the seal-in resistor105.

When the circuit breaker is in the open position illustrated by Fig. 2,the manually-operable switch 96 can be closed to energize and operatethe closing-release solenoid 67 thereby producing breaker closing. When,however, the breaker is in a closed position with its b switch 107 open,the manually-operable switch 96 is ineffective to produce operation ofthe solenoid 67. This is the case because with the b" switch 107 open,the seal-in resistor limits the current through the solenoid coil to avalue which is insufiicient to cause pick-up of the solenoid. Thus, withthe breaker closed, the b switch 107 prevents operation of the solenoid67 and thereby prevents attempted closure of the breaker, as is desired.

The seal-in resistor 105 cooperates with the closingrelease device 50 toprevent circuit-breaker pumping in the following manner. Assume that thebreaker is open with the various control switches in the position ofFig. 2 and that the operator closes switch 96 and holds it closed for aprotracted period. The closing release solenoid 67 would be operated toproduce breaker closing, thereby opening the b switch 107 and thecontrol switch 94. This would divert current through the seal-inresistor 105, which, in turn, would allow sufficient current to flowthrough the coil of solenoid 67 to maintain its armature 67a sealed-in,as shown in Fig. 4. Since the releasing device 50 cannot reset so longas the armature of the solenoid 67 is sealed-in and since the releasingdevice 50 is inoperative to produce another closingoperation untilreset, it will be apparent that so long as the manually-operable switch96 is held closed, the releasing device will be incapable of initiatinganother closing operation. Thus, if the breaker should be closed on afault and should automatically trip open in response thereto while theoperator was still holding the switch 96 closed, there would be norepeated closure even though the b switch 107 reclosed in response toreopening of the breaker. In other words, pumping would be effectivelyprevented.

The importance of resistor 105 will be apparent when the operation ofthe control scheme is considered without the resistor. For example,Without the resistor 105, when the control switch 94 and the b switch107 would be open in response to breaker-closing, they would deenergizethe solenoid 67 and allow the closing release device 50 to reset eventhough the operator was holding the switch 96 closed. If the breakerthen opened in response to a fault and the operator was sitll holdingthe switch 96 closed, the b.switch 107 followed by the control switch 94would close to produce energization and operation of the solenoid 67,thus producing the repeated closing operations, or pumping, which ourinvention avoids.

Fig. 5 illustrates a slightly modified form of our invention whichpermits us to use a small non-continuously rated solenoid for producingthe desired operation of the releasing device 50. This modified form ofour invention difiers from that of Figs. l-4 only in its inclusion of anormally-closed switch 110 connected in parallel with the seal-inresistor 105 and operated 7 to open position by the solenoid armature67a near the end of its operating stroke. This switch 110 serves toprevent continuous full-voltage energization of the solenoid 67 underthose conditions in which the operator fails to promptly open the'manually-operable switch 96 after the breaker has closed and thentripped open. Under such conditions, the solenoid armature 67a wouldremain sealed-in, as described in connection with Figs. 1-4, and theswitches 94 and 107 would be closed. Without the switch 110, theresistor 105 would be shorted out and full control voltage would then beapplied to the solenoid coil; but with the switch 110, which is thenopen, the resistor 105 is effectively maintained in series with thesolenoid coil, thus desirably limiting the voltage and current to whichthe coil is subjected. Thus, since the solenoid is subjected tofull-voltage only during the short interval required for operating itfrom its neutral to its operated position, we are able to utilize anintermittantly-rated solenoid smaller than would otherwise be possible.Thus, the switch 110 enables us to utilize the seal-in resistor 105 notonly to prevent circuit breaker pumping but also as a means forprotecting the solenoid from prolonged overcurrent.

Although we have illustrated our invention in connection with astored-energy type of closing mechanism, it is to be understood that itsapplication is not limited to such mechanisms. For example, Fig. 6 showsan electric motor-driven mechanism utilizing certain features of ourinvention. For convenience, those parts of Fig. 6 which correspond tosimilar parts in Figs. 1-4 have been given corresponding referencenumerals.

Referring to Fig. 6, the rotatable cam 24 when driven clockwise by theelectric motor 112 lifts the roller 25 to extend the toggle 10, 12 anddrive the switch member 8 toward closed position. When the cam 24 hasbeen driven through approximately a complete revolution from theposition of Fig. 6, the breaker will be fully closed.

The motor 112 is arranged to be energized from a suitable current source114, 115 upon closure of a normallyopen control switch 117, which isconnected in series with the motor. As will soon appear more clearly,the switch 117 acts only to initiate motor operation inasmuch as it isclosed for only a short interval. Thereafter, a seal-in switch 120connected in parallel with the control switch 117 acts to continueoperation of the motor when the control switch 117 is opened. Thisswitch 120, which is controlled by an auxiliary cam 121 connected to therotatable shaft of main cam 24, is closed in response to initial motoroperation and is opened near the end of a complete revolution of themain cam 24 to terminate motor operation.

For initiating a closing operation, a device 50 corresponding to theclosing release device 50 of Figs. l-4 is utilized. This device 50comprises a solenoid 67 which can be operated when the breaker is in theopen position of Fig. 6 by closing the manually-operable switch 96. Thiscompletes an energizing circuit extending through the switch 96, the bswitch 107, and the coil of the solenoid 67. The solenoid responds bymoving the actuating pawl 54 to the right into driving engagement withthe crankpin 59. This pivots the crank 60 clockwise about its pivot 42causing the crank to close'the switch 117. When the solenoid stroke hasbeen completed, the parts of the initiating device 50 are in a positioncorresponding to that of Fig. 4. That is, the pawl 54 has been movedfree of-the crankpin 59, permitting the spring 44 to return the crank 60back to its original position thereby causing the switch 117 to beopened.

This momentary closing of the control switch 117, which results from afull stroke of the solenoid 67, is suificient to cause the motor 112 todrive the cam 24 through a complete revolution in the mannerpreviouslydescribed, thereby producing a breaker-closing operation.

When the breaker closes, the b switch 107 is opened and control currentis thereby diverted through the sealin resistor connected in shunt withthe b switch 107. This maintains the solenoid sealed-in, holding theparts of the initiating device 50 in a position corresponding to that ofFig. 4. In this position, the initiating device is incapable ofactuating the crank 60 to initiate another closing operation. Aspreviously pointed out, it is necessary to reset the initiating device50 at least partially to the position of Fig. 6 before it is againcapable of actuating the crank 60 to effect another breaker-closingoperation.

Thus, if the breaker, after closing as above-described, trips open inresponse to a fault or the like and the operator is still holding themanually-operable switch 96 closed, no additional closing operationswould be initiated inasmuch as the initiating device 50 would then beheld in its sealed-in inoperative position corresponding to that shownin Fig. 4. Thus, circuit breaker pumping would be prevented in themodification of Fig. 6 in essentially the same manner as in that ofFigs. l-4.

Although our invention has been illustrated only in connection with theoperation-initiating device 50, it is to be understood that it isapplicable to other forms of operation-initiating devices, such as, forexample, those shown in our application S. N. 512,638, filed June 2,1955,. now Patent No. 2,769,874. All of these devices are characterizedby their ability to initiate operation of a closing mechanism inresponse to movement of a driving part from a neutral to an operatedposition and by their incapability of initiating another closingoperation so long as the driving part is held in its operated position.

While we have shown and described a particular embodiment of ourinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from theinvention in its broader aspects and we, therefore, intend in theappended claims to cover all such changes and modifications as fallwithin the true spirit and scope of our invention.

What we claim as new and .desire to secure by Letters Patent of theUnited States is:

1. In an electric circuit breaker, motive means operable to produceclosing of the breaker, electromagnetic means having a driving partoperable from a neutral to an operated position, control meansresponsive to movement of said driving part from said neutral to saidoperated position for causing said motive means to operate to producecircuit breaker closing, said control means being ineffective to againcause a breaker-closing operation of said motive means until saiddriving part is returned at least partially to its neutral position, aselectively-operable first switch connected in series-circuitrelationship with said electromagnetic means and closable to produceoperation of said electromagnetic means, a second switch connected inseries-circuit relationship with said electromagnetic means and withsaid first switch, switch-actuating means responsive to the operativeposition of said breaker for closing said second switch when the breakerisopen and for opening said second switch when the breaker is closed,said switch actuating means acting to hold said second switch open solong as the breaker is closed, and means etfective when said breaker isclosed for maintaining said electromagnetic means sufliciently energizedto hold said driving part in said operated position in the event thatsaid first switch is held closed during the time said second switch isopen, said switch-actuating means acting to close said second switch inresponse to those breakeropening operations which occur even while saidfirst switch is being held closed.

2. In an electric circuit breaker, motive means operable to produceclosing of the breaker, electromagnetic means having a driving partoperable from a neutral to an operated position, control meansresponsive to movement of said driving part from said neutral to saidoperated position for causing said motive means to operate to producecircuit-breaker closing, said control means being inetfective to againcause a breaker-closing operation of said motive means until saiddriving part is returned at least partially to its neutral position, aselectively-operable first switch connected in series-circuitrelationship with said electromagnetic means, a second switch connectedin series-circuit relationship with said electromagnetic means and withsaid first switch, means for closing said second switch when the breakeris open and for opening said second switch when the breaker is closed,impedance means connected in shunt relationship with said second switchand in series relationship with said first switch to provide a seal-incircuit effective when said breaker is closed for maintaining thedriving part of said electromagnetic means in its operated position inthe event that said first switch is held closed during the time saidsecond switch is open.

3. The combination of claim 2 in which said impedance means whenconnected in current-limiting series relationship with saidelectromagnetic means acts to limit the current through saidelectromagnetic means to a value which is insufiicient to produceoperation of said driving part out of its neutral position.

4. In an electric circuit breaker, motive means operable to produceclosing of the breaker, electromagnetic means having a driving partoperable from a neutral to an operated position, control meansresponsive to movement of said driving part from said neutral to saidoperated position for causing said motive means to operate to producecircuit breaker closing, said control means being ineffective to againcause a breaker-closing operation of said motive means until saiddriving part is returned at least partially to its neutral position, aselectively-operable first switch connected in series-circuitrelationship with said electromagnetic means, a second switch connectedin series-circuit relationship with said .electromagnetic means and withsaid first switch, means for closing said second switch when the breakeris open, and for opening said second switch when the breaker is closed,impedance means connected in shunt relationship with said second switchand in series relationship with said first switch and saidelectromagnetic means to provide a seal-in circuit effective when saidbreaker is closed for maintaining the driving part of saidelectromagnetic means in its operated position in the event that saidfirst switch is held closed during the time said second switch is open,a third switch connected in series with said second switch and in shuntwith said impedance means, and means for closing said third switchwhenever said driving part is in its neutral position and for openingsaid third switch whenever said driving part is in its operated positionwhereby to maintain said impedance means connected in current-limitingseries relationship with said electromagnetic means whenever saiddriving part is in its operated position.

5. In an electric circuit breaker, motive means operable to produceclosing of the breaker, electromagnetic means having a driving partoperable from a neutral to an operated position, control meansresponsive to movement of said driving part from said neutral to saidoperated position for causing said motive means to operate to producecircuit-breaker closing, said control means being inelfective to againcause a breaker-closing operation of said motive means until saiddriving part is returned at least partially to its neutral position, aselectively-operable first switch connected in series-circuit 10relationship with said electromagnetic means, a second switch connectedin series-circuit relationship with said electromagnetic means and withsaid first switch, means for closing said second switch when the breakeris open and for opening said second switch when the breaker is closed,impedance means connected in shunt relationship with said second switchand in series relationship with said first switch and saidelectromagnetic means to provide a seal-in circuit effective when saidbreaker is closed for maintaining the driving part of saidelectromagnetic means in its operated position in the event that saidfirst switch is held closed during the time said second switch is open,and means for maintaining said impedance means connected incurrent-limiting series relationship with said electromagnetic meanswhenever said driving part is in its operated position.

6. In an electric circuit breaker, motive means operable to produceclosing of the breaker, electromagnetic means having a driving partoperable from a neutral to an operated position, control meansresponsive to movement of said driving part from said neutral to saidoperated position for causing said motive means to operate to producecircuit-breaker closing, said control means being ineffective to againcause a breaker-closing operation of said motive means until saiddriving part is returned at least partially to its neutral position, aselectively-operable first switch connected in series-circuitrelationship with said electromagnetic means, a second switch connectedin series circuit relationship with said electromagnetic means and withsaid first switch, means for operating said second switch from closed toopen position in response to initiation of a breaker-closing operation,and means comprising a seal-in circuit shunting said second switch andeffective when said breaker is closed for maintaining said driving partin said operated position in the event that said first switch is heldclosed during the time said second switch is open.

7. In an electric circuit breaker, motive means operable to produceclosing of the breaker, electromagnetic means having a driving partoperable-from a neutral to an operated position, control meansresponsive to movement of said driving part from said neutral to saidoperated position for causing said motive means to operate to producecircuit-breaker closing, said control means being ineffective to againcause a breaker-closing operation of said motive means so long as saiddriving part is held in its operated position, a selectively-operablefirst switch connected in series-circuit relationship with saidelectromagnetic means, a second switch connected in series-circuitrelationship with said electromagnetic means and with said first switch,means for operating said second switch from closed to open position inresponse to initiation of a breaker-closing operation, and meanscomprising aseal-in circuit shunting said second switch and effectiveeven while said breaker is closed for maintaining said driving part insaid operated position in the event that said first switch is heldclosed during the time said second switch is open.

References Cited in the file of this patent UNITED STATES PATENTS

